diff --git a/RedPandaIDE/problems/freeprojectsetformat.cpp b/RedPandaIDE/problems/freeprojectsetformat.cpp
index e8e71012..4e79235b 100644
--- a/RedPandaIDE/problems/freeprojectsetformat.cpp
+++ b/RedPandaIDE/problems/freeprojectsetformat.cpp
@@ -2,7 +2,7 @@
 
 #include <QFile>
 #include <QXmlStreamReader>
-#
+#include <QXmlStreamWriter>
 
 QList<POJProblem> importFreeProblemSet(const QString &filename)
 {
@@ -14,7 +14,6 @@ QList<POJProblem> importFreeProblemSet(const QString &filename)
     xml.setDevice(&file);
     POJProblem currentProblem;
     POJProblemCase currentCase;
-    QString currentText;
     QString currentEleName;
     while(!xml.atEnd()) {
         xml.readNext();
@@ -94,3 +93,14 @@ QList<POJProblem> importFreeProblemSet(const QString &filename)
     }
     return problems;
 }
+
+void exportFreeProblemSet(const QList<POJProblem> &problems, const QString &filename)
+{
+    QFile file(filename);
+    if (!file.open(QFile::WriteOnly|QFile::Truncate))
+        return;
+    QXmlStreamWriter writer(&file);
+    writer.setAutoFormatting(true);
+    writer.writeStartDocument();
+    writer.writeEndDocument();
+}
diff --git a/RedPandaIDE/problems/freeprojectsetformat.h b/RedPandaIDE/problems/freeprojectsetformat.h
index 8b635000..ffac0ed2 100644
--- a/RedPandaIDE/problems/freeprojectsetformat.h
+++ b/RedPandaIDE/problems/freeprojectsetformat.h
@@ -4,6 +4,6 @@
 #include "ojproblemset.h"
 
 QList<POJProblem> importFreeProblemSet(const QString& filename);
-//void exportFreeProblemSet(const QList<POJProblem>& problems);
+void exportFreeProblemSet(const QList<POJProblem>& problems, const QString& filename);
 
 #endif // FREEPROJECTSETFORMAT_H